1. Field of the Invention
The disclosure relates to a backlight display technology field, and more particularly to an ultrathin planar light source apparatus.
2. The Related Arts
Light Emitting Diode (LED) is a new type power-saving light source with high competitiveness. The trend is gradually replacing the traditional light source. LED has some advantages such that highly luminous efficiency, good light quality, high color purity, suitable voltage-controlled, low power consumption and long life span. The backlight source provides the light source for the liquid crystal display (LCD). The backlight source mainly comprises the light source, the light guide plate, the optical films and the plastic frame. The backlight source is required to have the advantages of high brightness, long life span and uniform luminance. LED is widely used because of its many advantages in LCD backlight.
Since the introduction of the concept of the ultrathin LCD, the backlight mostly adopts the edge lit illumination. Increasing the brightness and ensuring the uniformity of brightness of the panel are achieved by using the light guide plate to guide the light scattering direction. LED lamp is required to be a good fit with the light guide plate in order to allow more light to enter the light guide plate. The principle of LED light-emitting is that the PN junction is powered to emit the light by itself. The emitting angle is isotopically and uniformly scattered through 360 degrees. The emitting angle of the SMD LED is 120 degrees in general. A great loss of light is produced because the light emitting from the LED lamps does not enter the light guide plate completely.
In order to increase the light utilization efficiency, there is one technical solution in which the light incident side of the light guide plate near the LED light source is made as a wedge. It can increase the area of the light incident side to receive more light beams and increase the light utilization efficiency. This technical solution cannot apply in the ultrathin apparatus because of the increasing thickness of the light guide plate.